Process of drawing sheet-glass



, H. G. SLINGLUFF. PROCESS 0F DRAWING SHEET GLASS.

'Patented Mayl 3,A 1921.

APPLICAIION FILED MA'Y22. 1 919.

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To all 'whom t may ooncem.'

UNITED srA'rEs PATENT orEicE.

BARRY e. sLINeLUrr, or MoUNfr venirmi, onmnssie'ivon 'ro PITTSBURGH man.

epassv COMPANY, a conrona'rion or PENNSYLVANIA.

PROCESS OF DRAWING SHEET-GLASS.

specification 4of Letters-retient. V

vmammal May 3, I1921.

Application led May 22, 1919*., SerialA No. 298,966.

Be vit known that I, HARRY G. SHNGLUFF, a citizen of the United States, and a resident of Mount Vernon, in the county of Knox and State of Ohio, have made a new and useful Invention in Processes of Drawing Sheet-Glass, ofwhich the following is a specication.

The invention relates to the drawing of glass in the forin'of sheets and has to do primarily vwith a rocedure whereby the edges ofthe sheet in process of generation are maintained in position and prevented from working inward and narrowing the sheet as the drawing progresses. -The 1nvention-has for its principal object the r0- vision of a simple means of proce .ure which may be carried outv byihand manipulation or lby an automatic device whereby the position' of the edges of the sheet being drawn are maintained in their proper p osition throughout the `draw and their thickness regulated, thus securing a sheet of continuously uniform width. -The procedure is 225,190, sied March est illustrated fin the accompanying drawings, wherein:

Figure 1 is a transverse section through a forehearth ordrawing tank from which a sheet of'glass is bein 'drawn in accordance with my invention' ig. 2 is a plan view of the apparatus of Fig. 1; Fig. 3 is an enlarged4 side elevation view showing one edge of the sheet and illustrating the. step of t e process in which the invention particularly resides; Fig. 4: is a plan view of the sheet and bath illustrated in Fig. 3,' and F'ig.,5 is a perspective view showing a modified forni of tool for carrying out -t e operation.

Figs. land 2 illustrate the drawing apparatus and operation similar to that illustratedl in my pending application Serial No'.

1918. In carrying out this yoperation a sheet of glass. is drawn from a forehearth or tank containing a relatively large dee body of glass, and in order to maintain t e width of the sheet being draw'ii, pockets ofl relatively cooler glass vare provided at-the sides of the furnace, such pockets of glass serving as viscous bonds between the ed e of the sheet and the clay work of the bloc s. Ithas been kfound in the use of-ths apparatus that particularly .in the initial stages of the formation of the sheet, there is a tendency ofthe edges 66 to draw in and thicken, and it is the purpose of'this invention to provide means whereby this tendency is counteracted and the edges of the sheet lmaintained in their-proper p0- sitions and maintained at proper thickness.

I have found that this object can be accomplished by the` use of the cooling tool or rod by which the glass adjacent the edges of the sheet-is treated at intervals, depending upon the conditions. Briefly stated, this treatment'consists in pressing the end of the tool. into the glass on either side ofthe edge which it is desired 'to maintain in position. The end of the tool is (preferably curved or rounded and is presse into the glass first on one side of the edge of the sheet and then on the other, the tool at such time being drawn outwardly, so that elongated depressions are produced on each side of the edge.

This operation not only thins the edge, but

also cools it and by making the glass more viscous, tends to prevent any inward movement of the edge.

The manner in which the invention is practised will be understood by reference to the drawings, which illustrate the procedure in a simple and more or lessdiagrammatic manner, only' so much of the apparatus einployed bein illustrated as is necessar to make clear t e method of operation. igs. 1 and 2 illustrate a portion of the drawing tank or forehearth with the lower portion lof the sheet which is being drawn, the bait and other drawing a paratus for continuously drawing the s eet not bei illustrated. vIn this construction-f1M is t e 'tank containing the molten mass of glass 2, and 3 is the sheet being drawn with' is edges in proximity to the drawing blocks .4. These drawing blocks are providedwith recesses or pockets 5, which are filled with glass normally The extreme edge of the sheet is shown in enlarged detail in Figs. 3 and 4, and it is t0 this portion ofthe glass. thatthe tool for maintaining the edge in position is applied. This tool is in the form of a rod of iron 6, preferably about five or six feet long and aving its end curvedl as indicated at Fig. 3. In the use of the tool the end 7 is pressed into the glass on either side of the edge ofthev sheet' forming the recesses 8. These recesses or pockets may vary in size and dimension but are ordinarily one or two inches deep and perhaps three inches p somewhat cooler than the glass'in' vthe main body o'f the tank. n

long. They are formed by pressing the end of the tool into the glass and then moving it outward. These depressions or pockets are formed close to the sides of the edge so that the portion 9 (Fig. 4) is somewhat thinned, while the outward movement of the tool tends to pull this edge'of the sheet outward slightly. The glass from which the edge is drawn, and particularly the portion 10 (F i V4) is cooled bythe application of the too and by exposure to the cooling action of the air, thus makingthe glass from which the vedge of the sheet is formed, more viscous, and in this way tending t0 maintain the width of the sheet and increase the stiffness of the glass between the. edge of the sheet and the clay of the drawing block 4. The recesses may be parallel to the plane of the sheet but are ordinarily somewhat inclined as indicated in Fig. 4.

The tool is preferablyy used more frequently at the beginning of the drawing, at which time such tool may be used first on one side of the sheet and then on the other about every half minute. As the drawing progresses the frequency at which the tool must be used decreases andl after a considerable lapse of time the conditions in the bath may becomeso established and stabilized that the tool need be used only at long intervals. Theportion of the bath from which the drawing of the edges occurs, is

relatively stili", so that the depressions 8 remain in the glass a considerable length of time, althoug in most cases they have about disappeared when the timearrives for using the tool again.

The tool has been used in most cases in connection with drawing blocks such as those indicated in Figs. l and 2, but the operation is not restricted to use in connection with blocks of this type, the procedure having the same function and utility with respect to maintaining thewidth of the sheet regardless of the type of tank and drawing blocks which are employed. Therecesses 8 are preferably not formed at the same time, the tool being used first on one` side and then on the other, as heretofore described, but if desired, a tool may be employed such as illustrated in Fig. 5, wherein the handle portion 1l is provided with a pair of ends 12, so that two recesses may be formed at the Same time. The invention is also not limited to the formation of the recesses or pockets by a hand operated tool, as a tool may be used which is poweroperated, and which makes engagement with the glass at predetermined intervals. Such a tool would preferably have an end approximating in shape that used on the hand tool, but such shape might be varied, depending uponV conditions and depending upon the movement given to the tool. Obviously a tool such as that shown in Fig. 5 might also be operated by power means automatically.

What I yclaim is: 4

l. In the process of drawing a glass sheet from a molten bath, the step ofmaintaining the position of the edge of the sheet which consists in depressing elongatedl recesses or pockets at intervals in the body of molten glass with a cooling tool on each side of the edge and in close proximity thereto.

2. In the process of drawing a glass sheet from a molten bath, the step of maintaining the position of the edge of the sheet which consists inpressing a cooling tool into the body of molten glass at intervals on either side ofsaid edge in close proximity thereto.

3. In the process of drawing a glass sheet from a molten bath, the ste ofmaintaining the position of the edge o the sheet which consists in pressing a cooling tool into the body of molten glass at intervals on either side of saidy edge in close proximity thereto, Said tool being given a downward and outward movement tending to thin the edge and move it outwardly.

4. In the process of drawing a glass sheet from a molten bath, the step of maintainin the position of the edge of the sheet whic consists in pressing a cooling tool into the body of molten glass at intervals on either side of said edge in close proximity thereto, thus providing a pair `of'coolin recesses in the glass with a ridge of glass t erebetweenl constituting a lateral extension of such edge.

In testimony whereof, I lhave hereunto subscribed my name this 14th day of May,

HARRY G. SLINGLUFF. 

